How many atoms are in 3.5 grams of silicon?

1 Answer
A08
Mar 24, 2016

#=7.505xx10^22# atoms. (rounded to third place of decimal)

Explanation:

Average atomic weight of Silicon, Si atom is #28.0855# units.

We know from Mole concept that #1# mole is #6.022xx10^23# of anything. This number is called Avogadro's number.

Also that #1# mole of Silicon weighs #28.0855# g.

Therefore,
#28.0855# g of Silicon contains #6.022xx10^23# of Silicon atoms.
#3.5# g of Silicon contains number of atoms #=(6.022xx10^23)/28.0855xx3.5#
#=7.505xx10^22# atoms. (rounded to third place of decimal)

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